Initial vendor packages

Signed-off-by: Valentin Popov <valentin@popov.link>

14 files changed, 1902 insertions, 0 deletions

diff --git a/vendor/backtrace/src/symbolize/gimli/coff.rs b/vendor/backtrace/src/symbolize/gimli/coff.rs
new file mode 100644
index 0000000..759c827
--- /dev/null
+++ b/vendor/backtrace/src/symbolize/gimli/coff.rs
@@ -0,0 +1,118 @@
+use super::{gimli, Context, Endian, EndianSlice, Mapping, Path, Stash, Vec};
+use alloc::sync::Arc;
+use core::convert::TryFrom;
+use object::pe::{ImageDosHeader, ImageSymbol};
+use object::read::coff::ImageSymbol as _;
+use object::read::pe::{ImageNtHeaders, ImageOptionalHeader, SectionTable};
+use object::read::StringTable;
+use object::LittleEndian as LE;
+
+#[cfg(target_pointer_width = "32")]
+type Pe = object::pe::ImageNtHeaders32;
+#[cfg(target_pointer_width = "64")]
+type Pe = object::pe::ImageNtHeaders64;
+
+impl Mapping {
+    pub fn new(path: &Path) -> Option<Mapping> {
+        let map = super::mmap(path)?;
+        Mapping::mk(map, |data, stash| {
+            Context::new(stash, Object::parse(data)?, None, None)
+        })
+    }
+}
+
+pub struct Object<'a> {
+    data: &'a [u8],
+    sections: SectionTable<'a>,
+    symbols: Vec<(usize, &'a ImageSymbol)>,
+    strings: StringTable<'a>,
+}
+
+pub fn get_image_base(data: &[u8]) -> Option<usize> {
+    let dos_header = ImageDosHeader::parse(data).ok()?;
+    let mut offset = dos_header.nt_headers_offset().into();
+    let (nt_headers, _) = Pe::parse(data, &mut offset).ok()?;
+    usize::try_from(nt_headers.optional_header().image_base()).ok()
+}
+
+impl<'a> Object<'a> {
+    fn parse(data: &'a [u8]) -> Option<Object<'a>> {
+        let dos_header = ImageDosHeader::parse(data).ok()?;
+        let mut offset = dos_header.nt_headers_offset().into();
+        let (nt_headers, _) = Pe::parse(data, &mut offset).ok()?;
+        let sections = nt_headers.sections(data, offset).ok()?;
+        let symtab = nt_headers.symbols(data).ok()?;
+        let strings = symtab.strings();
+        let image_base = usize::try_from(nt_headers.optional_header().image_base()).ok()?;
+
+        // Collect all the symbols into a local vector which is sorted
+        // by address and contains enough data to learn about the symbol
+        // name. Note that we only look at function symbols and also
+        // note that the sections are 1-indexed because the zero section
+        // is special (apparently).
+        let mut symbols = Vec::new();
+        let mut i = 0;
+        let len = symtab.len();
+        while i < len {
+            let sym = symtab.symbol(i).ok()?;
+            i += 1 + sym.number_of_aux_symbols as usize;
+            let section_number = sym.section_number.get(LE);
+            if sym.derived_type() != object::pe::IMAGE_SYM_DTYPE_FUNCTION || section_number == 0 {
+                continue;
+            }
+            let addr = usize::try_from(sym.value.get(LE)).ok()?;
+            let section = sections
+                .section(usize::try_from(section_number).ok()?)
+                .ok()?;
+            let va = usize::try_from(section.virtual_address.get(LE)).ok()?;
+            symbols.push((addr + va + image_base, sym));
+        }
+        symbols.sort_unstable_by_key(|x| x.0);
+        Some(Object {
+            data,
+            sections,
+            strings,
+            symbols,
+        })
+    }
+
+    pub fn section(&self, _: &Stash, name: &str) -> Option<&'a [u8]> {
+        Some(
+            self.sections
+                .section_by_name(self.strings, name.as_bytes())?
+                .1
+                .pe_data(self.data)
+                .ok()?,
+        )
+    }
+
+    pub fn search_symtab<'b>(&'b self, addr: u64) -> Option<&'b [u8]> {
+        // Note that unlike other formats COFF doesn't embed the size of
+        // each symbol. As a last ditch effort search for the *closest*
+        // symbol to a particular address and return that one. This gets
+        // really wonky once symbols start getting removed because the
+        // symbols returned here can be totally incorrect, but we have
+        // no idea of knowing how to detect that.
+        let addr = usize::try_from(addr).ok()?;
+        let i = match self.symbols.binary_search_by_key(&addr, |p| p.0) {
+            Ok(i) => i,
+            // typically `addr` isn't in the array, but `i` is where
+            // we'd insert it, so the previous position must be the
+            // greatest less than `addr`
+            Err(i) => i.checked_sub(1)?,
+        };
+        self.symbols[i].1.name(self.strings).ok()
+    }
+
+    pub(super) fn search_object_map(&self, _addr: u64) -> Option<(&Context<'_>, u64)> {
+        None
+    }
+}
+
+pub(super) fn handle_split_dwarf<'data>(
+    _package: Option<&gimli::DwarfPackage<EndianSlice<'data, Endian>>>,
+    _stash: &'data Stash,
+    _load: addr2line::SplitDwarfLoad<EndianSlice<'data, Endian>>,
+) -> Option<Arc<gimli::Dwarf<EndianSlice<'data, Endian>>>> {
+    None
+}
diff --git a/vendor/backtrace/src/symbolize/gimli/elf.rs b/vendor/backtrace/src/symbolize/gimli/elf.rs
new file mode 100644
index 0000000..b0eec07
--- /dev/null
+++ b/vendor/backtrace/src/symbolize/gimli/elf.rs
@@ -0,0 +1,495 @@
+use super::mystd::ffi::{OsStr, OsString};
+use super::mystd::fs;
+use super::mystd::os::unix::ffi::{OsStrExt, OsStringExt};
+use super::mystd::path::{Path, PathBuf};
+use super::Either;
+use super::{gimli, Context, Endian, EndianSlice, Mapping, Stash, Vec};
+use alloc::sync::Arc;
+use core::convert::{TryFrom, TryInto};
+use core::str;
+use object::elf::{ELFCOMPRESS_ZLIB, ELF_NOTE_GNU, NT_GNU_BUILD_ID, SHF_COMPRESSED};
+use object::read::elf::{CompressionHeader, FileHeader, SectionHeader, SectionTable, Sym};
+use object::read::StringTable;
+use object::{BigEndian, Bytes, NativeEndian};
+
+#[cfg(target_pointer_width = "32")]
+type Elf = object::elf::FileHeader32<NativeEndian>;
+#[cfg(target_pointer_width = "64")]
+type Elf = object::elf::FileHeader64<NativeEndian>;
+
+impl Mapping {
+    pub fn new(path: &Path) -> Option<Mapping> {
+        let map = super::mmap(path)?;
+        Mapping::mk_or_other(map, |map, stash| {
+            let object = Object::parse(&map)?;
+
+            // Try to locate an external debug file using the build ID.
+            if let Some(path_debug) = object.build_id().and_then(locate_build_id) {
+                if let Some(mapping) = Mapping::new_debug(path, path_debug, None) {
+                    return Some(Either::A(mapping));
+                }
+            }
+
+            // Try to locate an external debug file using the GNU debug link section.
+            if let Some((path_debug, crc)) = object.gnu_debuglink_path(path) {
+                if let Some(mapping) = Mapping::new_debug(path, path_debug, Some(crc)) {
+                    return Some(Either::A(mapping));
+                }
+            }
+
+            let dwp = Mapping::load_dwarf_package(path, stash);
+
+            Context::new(stash, object, None, dwp).map(Either::B)
+        })
+    }
+
+    /// Load debuginfo from an external debug file.
+    fn new_debug(original_path: &Path, path: PathBuf, crc: Option<u32>) -> Option<Mapping> {
+        let map = super::mmap(&path)?;
+        Mapping::mk(map, |map, stash| {
+            let object = Object::parse(&map)?;
+
+            if let Some(_crc) = crc {
+                // TODO: check crc
+            }
+
+            // Try to locate a supplementary object file.
+            let mut sup = None;
+            if let Some((path_sup, build_id_sup)) = object.gnu_debugaltlink_path(&path) {
+                if let Some(map_sup) = super::mmap(&path_sup) {
+                    let map_sup = stash.cache_mmap(map_sup);
+                    if let Some(sup_) = Object::parse(map_sup) {
+                        if sup_.build_id() == Some(build_id_sup) {
+                            sup = Some(sup_);
+                        }
+                    }
+                }
+            }
+
+            let dwp = Mapping::load_dwarf_package(original_path, stash);
+
+            Context::new(stash, object, sup, dwp)
+        })
+    }
+
+    /// Try to locate a DWARF package file.
+    fn load_dwarf_package<'data>(path: &Path, stash: &'data Stash) -> Option<Object<'data>> {
+        let mut path_dwp = path.to_path_buf();
+        let dwp_extension = path
+            .extension()
+            .map(|previous_extension| {
+                let mut previous_extension = previous_extension.to_os_string();
+                previous_extension.push(".dwp");
+                previous_extension
+            })
+            .unwrap_or_else(|| "dwp".into());
+        path_dwp.set_extension(dwp_extension);
+        if let Some(map_dwp) = super::mmap(&path_dwp) {
+            let map_dwp = stash.cache_mmap(map_dwp);
+            if let Some(dwp_) = Object::parse(map_dwp) {
+                return Some(dwp_);
+            }
+        }
+
+        None
+    }
+}
+
+struct ParsedSym {
+    address: u64,
+    size: u64,
+    name: u32,
+}
+
+pub struct Object<'a> {
+    /// Zero-sized type representing the native endianness.
+    ///
+    /// We could use a literal instead, but this helps ensure correctness.
+    endian: NativeEndian,
+    /// The entire file data.
+    data: &'a [u8],
+    sections: SectionTable<'a, Elf>,
+    strings: StringTable<'a>,
+    /// List of pre-parsed and sorted symbols by base address.
+    syms: Vec<ParsedSym>,
+}
+
+impl<'a> Object<'a> {
+    fn parse(data: &'a [u8]) -> Option<Object<'a>> {
+        let elf = Elf::parse(data).ok()?;
+        let endian = elf.endian().ok()?;
+        let sections = elf.sections(endian, data).ok()?;
+        let mut syms = sections
+            .symbols(endian, data, object::elf::SHT_SYMTAB)
+            .ok()?;
+        if syms.is_empty() {
+            syms = sections
+                .symbols(endian, data, object::elf::SHT_DYNSYM)
+                .ok()?;
+        }
+        let strings = syms.strings();
+
+        let mut syms = syms
+            .iter()
+            // Only look at function/object symbols. This mirrors what
+            // libbacktrace does and in general we're only symbolicating
+            // function addresses in theory. Object symbols correspond
+            // to data, and maybe someone's crazy enough to have a
+            // function go into static data?
+            .filter(|sym| {
+                let st_type = sym.st_type();
+                st_type == object::elf::STT_FUNC || st_type == object::elf::STT_OBJECT
+            })
+            // skip anything that's in an undefined section header,
+            // since it means it's an imported function and we're only
+            // symbolicating with locally defined functions.
+            .filter(|sym| sym.st_shndx(endian) != object::elf::SHN_UNDEF)
+            .map(|sym| {
+                let address = sym.st_value(endian).into();
+                let size = sym.st_size(endian).into();
+                let name = sym.st_name(endian);
+                ParsedSym {
+                    address,
+                    size,
+                    name,
+                }
+            })
+            .collect::<Vec<_>>();
+        syms.sort_unstable_by_key(|s| s.address);
+        Some(Object {
+            endian,
+            data,
+            sections,
+            strings,
+            syms,
+        })
+    }
+
+    pub fn section(&self, stash: &'a Stash, name: &str) -> Option<&'a [u8]> {
+        if let Some(section) = self.section_header(name) {
+            let mut data = Bytes(section.data(self.endian, self.data).ok()?);
+
+            // Check for DWARF-standard (gABI) compression, i.e., as generated
+            // by ld's `--compress-debug-sections=zlib-gabi` flag.
+            let flags: u64 = section.sh_flags(self.endian).into();
+            if (flags & u64::from(SHF_COMPRESSED)) == 0 {
+                // Not compressed.
+                return Some(data.0);
+            }
+
+            let header = data.read::<<Elf as FileHeader>::CompressionHeader>().ok()?;
+            if header.ch_type(self.endian) != ELFCOMPRESS_ZLIB {
+                // Zlib compression is the only known type.
+                return None;
+            }
+            let size = usize::try_from(header.ch_size(self.endian)).ok()?;
+            let buf = stash.allocate(size);
+            decompress_zlib(data.0, buf)?;
+            return Some(buf);
+        }
+
+        // Check for the nonstandard GNU compression format, i.e., as generated
+        // by ld's `--compress-debug-sections=zlib-gnu` flag. This means that if
+        // we're actually asking for `.debug_info` then we need to look up a
+        // section named `.zdebug_info`.
+        if !name.starts_with(".debug_") {
+            return None;
+        }
+        let debug_name = name[7..].as_bytes();
+        let compressed_section = self
+            .sections
+            .iter()
+            .filter_map(|header| {
+                let name = self.sections.section_name(self.endian, header).ok()?;
+                if name.starts_with(b".zdebug_") && &name[8..] == debug_name {
+                    Some(header)
+                } else {
+                    None
+                }
+            })
+            .next()?;
+        let mut data = Bytes(compressed_section.data(self.endian, self.data).ok()?);
+        if data.read_bytes(8).ok()?.0 != b"ZLIB\0\0\0\0" {
+            return None;
+        }
+        let size = usize::try_from(data.read::<object::U32Bytes<_>>().ok()?.get(BigEndian)).ok()?;
+        let buf = stash.allocate(size);
+        decompress_zlib(data.0, buf)?;
+        Some(buf)
+    }
+
+    fn section_header(&self, name: &str) -> Option<&<Elf as FileHeader>::SectionHeader> {
+        self.sections
+            .section_by_name(self.endian, name.as_bytes())
+            .map(|(_index, section)| section)
+    }
+
+    pub fn search_symtab<'b>(&'b self, addr: u64) -> Option<&'b [u8]> {
+        // Same sort of binary search as Windows above
+        let i = match self.syms.binary_search_by_key(&addr, |sym| sym.address) {
+            Ok(i) => i,
+            Err(i) => i.checked_sub(1)?,
+        };
+        let sym = self.syms.get(i)?;
+        if sym.address <= addr && addr <= sym.address + sym.size {
+            self.strings.get(sym.name).ok()
+        } else {
+            None
+        }
+    }
+
+    pub(super) fn search_object_map(&self, _addr: u64) -> Option<(&Context<'_>, u64)> {
+        None
+    }
+
+    fn build_id(&self) -> Option<&'a [u8]> {
+        for section in self.sections.iter() {
+            if let Ok(Some(mut notes)) = section.notes(self.endian, self.data) {
+                while let Ok(Some(note)) = notes.next() {
+                    if note.name() == ELF_NOTE_GNU && note.n_type(self.endian) == NT_GNU_BUILD_ID {
+                        return Some(note.desc());
+                    }
+                }
+            }
+        }
+        None
+    }
+
+    // The contents of the ".gnu_debuglink" section is documented at:
+    // https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html
+    fn gnu_debuglink_path(&self, path: &Path) -> Option<(PathBuf, u32)> {
+        let section = self.section_header(".gnu_debuglink")?;
+        let data = section.data(self.endian, self.data).ok()?;
+        let len = data.iter().position(|x| *x == 0)?;
+        let filename = &data[..len];
+        let offset = (len + 1 + 3) & !3;
+        let crc_bytes = data
+            .get(offset..offset + 4)
+            .and_then(|bytes| bytes.try_into().ok())?;
+        let crc = u32::from_ne_bytes(crc_bytes);
+        let path_debug = locate_debuglink(path, filename)?;
+        Some((path_debug, crc))
+    }
+
+    // The format of the ".gnu_debugaltlink" section is based on gdb.
+    fn gnu_debugaltlink_path(&self, path: &Path) -> Option<(PathBuf, &'a [u8])> {
+        let section = self.section_header(".gnu_debugaltlink")?;
+        let data = section.data(self.endian, self.data).ok()?;
+        let len = data.iter().position(|x| *x == 0)?;
+        let filename = &data[..len];
+        let build_id = &data[len + 1..];
+        let path_sup = locate_debugaltlink(path, filename, build_id)?;
+        Some((path_sup, build_id))
+    }
+}
+
+fn decompress_zlib(input: &[u8], output: &mut [u8]) -> Option<()> {
+    use miniz_oxide::inflate::core::inflate_flags::{
+        TINFL_FLAG_PARSE_ZLIB_HEADER, TINFL_FLAG_USING_NON_WRAPPING_OUTPUT_BUF,
+    };
+    use miniz_oxide::inflate::core::{decompress, DecompressorOxide};
+    use miniz_oxide::inflate::TINFLStatus;
+
+    let (status, in_read, out_read) = decompress(
+        &mut DecompressorOxide::new(),
+        input,
+        output,
+        0,
+        TINFL_FLAG_USING_NON_WRAPPING_OUTPUT_BUF | TINFL_FLAG_PARSE_ZLIB_HEADER,
+    );
+    if status == TINFLStatus::Done && in_read == input.len() && out_read == output.len() {
+        Some(())
+    } else {
+        None
+    }
+}
+
+const DEBUG_PATH: &[u8] = b"/usr/lib/debug";
+
+fn debug_path_exists() -> bool {
+    cfg_if::cfg_if! {
+        if #[cfg(any(target_os = "freebsd", target_os = "linux"))] {
+            use core::sync::atomic::{AtomicU8, Ordering};
+            static DEBUG_PATH_EXISTS: AtomicU8 = AtomicU8::new(0);
+
+            let mut exists = DEBUG_PATH_EXISTS.load(Ordering::Relaxed);
+            if exists == 0 {
+                exists = if Path::new(OsStr::from_bytes(DEBUG_PATH)).is_dir() {
+                    1
+                } else {
+                    2
+                };
+                DEBUG_PATH_EXISTS.store(exists, Ordering::Relaxed);
+            }
+            exists == 1
+        } else {
+            false
+        }
+    }
+}
+
+/// Locate a debug file based on its build ID.
+///
+/// The format of build id paths is documented at:
+/// https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html
+fn locate_build_id(build_id: &[u8]) -> Option<PathBuf> {
+    const BUILD_ID_PATH: &[u8] = b"/usr/lib/debug/.build-id/";
+    const BUILD_ID_SUFFIX: &[u8] = b".debug";
+
+    if build_id.len() < 2 {
+        return None;
+    }
+
+    if !debug_path_exists() {
+        return None;
+    }
+
+    let mut path =
+        Vec::with_capacity(BUILD_ID_PATH.len() + BUILD_ID_SUFFIX.len() + build_id.len() * 2 + 1);
+    path.extend(BUILD_ID_PATH);
+    path.push(hex(build_id[0] >> 4));
+    path.push(hex(build_id[0] & 0xf));
+    path.push(b'/');
+    for byte in &build_id[1..] {
+        path.push(hex(byte >> 4));
+        path.push(hex(byte & 0xf));
+    }
+    path.extend(BUILD_ID_SUFFIX);
+    Some(PathBuf::from(OsString::from_vec(path)))
+}
+
+fn hex(byte: u8) -> u8 {
+    if byte < 10 {
+        b'0' + byte
+    } else {
+        b'a' + byte - 10
+    }
+}
+
+/// Locate a file specified in a `.gnu_debuglink` section.
+///
+/// `path` is the file containing the section.
+/// `filename` is from the contents of the section.
+///
+/// Search order is based on gdb, documented at:
+/// https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html
+///
+/// gdb also allows the user to customize the debug search path, but we don't.
+///
+/// gdb also supports debuginfod, but we don't yet.
+fn locate_debuglink(path: &Path, filename: &[u8]) -> Option<PathBuf> {
+    let path = fs::canonicalize(path).ok()?;
+    let parent = path.parent()?;
+    let mut f = PathBuf::from(OsString::with_capacity(
+        DEBUG_PATH.len() + parent.as_os_str().len() + filename.len() + 2,
+    ));
+    let filename = Path::new(OsStr::from_bytes(filename));
+
+    // Try "/parent/filename" if it differs from "path"
+    f.push(parent);
+    f.push(filename);
+    if f != path && f.is_file() {
+        return Some(f);
+    }
+
+    // Try "/parent/.debug/filename"
+    let mut s = OsString::from(f);
+    s.clear();
+    f = PathBuf::from(s);
+    f.push(parent);
+    f.push(".debug");
+    f.push(filename);
+    if f.is_file() {
+        return Some(f);
+    }
+
+    if debug_path_exists() {
+        // Try "/usr/lib/debug/parent/filename"
+        let mut s = OsString::from(f);
+        s.clear();
+        f = PathBuf::from(s);
+        f.push(OsStr::from_bytes(DEBUG_PATH));
+        f.push(parent.strip_prefix("/").unwrap());
+        f.push(filename);
+        if f.is_file() {
+            return Some(f);
+        }
+    }
+
+    None
+}
+
+/// Locate a file specified in a `.gnu_debugaltlink` section.
+///
+/// `path` is the file containing the section.
+/// `filename` and `build_id` are the contents of the section.
+///
+/// Search order is based on gdb:
+/// - filename, which is either absolute or relative to `path`
+/// - the build ID path under `BUILD_ID_PATH`
+///
+/// gdb also allows the user to customize the debug search path, but we don't.
+///
+/// gdb also supports debuginfod, but we don't yet.
+fn locate_debugaltlink(path: &Path, filename: &[u8], build_id: &[u8]) -> Option<PathBuf> {
+    let filename = Path::new(OsStr::from_bytes(filename));
+    if filename.is_absolute() {
+        if filename.is_file() {
+            return Some(filename.into());
+        }
+    } else {
+        let path = fs::canonicalize(path).ok()?;
+        let parent = path.parent()?;
+        let mut f = PathBuf::from(parent);
+        f.push(filename);
+        if f.is_file() {
+            return Some(f);
+        }
+    }
+
+    locate_build_id(build_id)
+}
+
+fn convert_path<R: gimli::Reader>(r: &R) -> Result<PathBuf, gimli::Error> {
+    let bytes = r.to_slice()?;
+    Ok(PathBuf::from(OsStr::from_bytes(&bytes)))
+}
+
+pub(super) fn handle_split_dwarf<'data>(
+    package: Option<&gimli::DwarfPackage<EndianSlice<'data, Endian>>>,
+    stash: &'data Stash,
+    load: addr2line::SplitDwarfLoad<EndianSlice<'data, Endian>>,
+) -> Option<Arc<gimli::Dwarf<EndianSlice<'data, Endian>>>> {
+    if let Some(dwp) = package.as_ref() {
+        if let Ok(Some(cu)) = dwp.find_cu(load.dwo_id, &load.parent) {
+            return Some(Arc::new(cu));
+        }
+    }
+
+    let mut path = PathBuf::new();
+    if let Some(p) = load.comp_dir.as_ref() {
+        path.push(convert_path(p).ok()?);
+    }
+
+    path.push(convert_path(load.path.as_ref()?).ok()?);
+
+    if let Some(map_dwo) = super::mmap(&path) {
+        let map_dwo = stash.cache_mmap(map_dwo);
+        if let Some(dwo) = Object::parse(map_dwo) {
+            return gimli::Dwarf::load(|id| -> Result<_, ()> {
+                let data = id
+                    .dwo_name()
+                    .and_then(|name| dwo.section(stash, name))
+                    .unwrap_or(&[]);
+                Ok(EndianSlice::new(data, Endian))
+            })
+            .ok()
+            .map(|mut dwo_dwarf| {
+                dwo_dwarf.make_dwo(&load.parent);
+                Arc::new(dwo_dwarf)
+            });
+        }
+    }
+
+    None
+}
diff --git a/vendor/backtrace/src/symbolize/gimli/libs_dl_iterate_phdr.rs b/vendor/backtrace/src/symbolize/gimli/libs_dl_iterate_phdr.rs
new file mode 100644
index 0000000..9f0304c
--- /dev/null
+++ b/vendor/backtrace/src/symbolize/gimli/libs_dl_iterate_phdr.rs
@@ -0,0 +1,71 @@
+// Other Unix (e.g. Linux) platforms use ELF as an object file format
+// and typically implement an API called `dl_iterate_phdr` to load
+// native libraries.
+
+use super::mystd::borrow::ToOwned;
+use super::mystd::env;
+use super::mystd::ffi::{CStr, OsStr};
+use super::mystd::os::unix::prelude::*;
+use super::{Library, LibrarySegment, OsString, Vec};
+use core::slice;
+
+pub(super) fn native_libraries() -> Vec<Library> {
+    let mut ret = Vec::new();
+    unsafe {
+        libc::dl_iterate_phdr(Some(callback), &mut ret as *mut Vec<_> as *mut _);
+    }
+    return ret;
+}
+
+fn infer_current_exe(base_addr: usize) -> OsString {
+    if let Ok(entries) = super::parse_running_mmaps::parse_maps() {
+        let opt_path = entries
+            .iter()
+            .find(|e| e.ip_matches(base_addr) && e.pathname().len() > 0)
+            .map(|e| e.pathname())
+            .cloned();
+        if let Some(path) = opt_path {
+            return path;
+        }
+    }
+    env::current_exe().map(|e| e.into()).unwrap_or_default()
+}
+
+// `info` should be a valid pointers.
+// `vec` should be a valid pointer to a `std::Vec`.
+unsafe extern "C" fn callback(
+    info: *mut libc::dl_phdr_info,
+    _size: libc::size_t,
+    vec: *mut libc::c_void,
+) -> libc::c_int {
+    let info = &*info;
+    let libs = &mut *(vec as *mut Vec<Library>);
+    let is_main_prog = info.dlpi_name.is_null() || *info.dlpi_name == 0;
+    let name = if is_main_prog {
+        // The man page for dl_iterate_phdr says that the first object visited by
+        // callback is the main program; so the first time we encounter a
+        // nameless entry, we can assume its the main program and try to infer its path.
+        // After that, we cannot continue that assumption, and we use an empty string.
+        if libs.is_empty() {
+            infer_current_exe(info.dlpi_addr as usize)
+        } else {
+            OsString::new()
+        }
+    } else {
+        let bytes = CStr::from_ptr(info.dlpi_name).to_bytes();
+        OsStr::from_bytes(bytes).to_owned()
+    };
+    let headers = slice::from_raw_parts(info.dlpi_phdr, info.dlpi_phnum as usize);
+    libs.push(Library {
+        name,
+        segments: headers
+            .iter()
+            .map(|header| LibrarySegment {
+                len: (*header).p_memsz as usize,
+                stated_virtual_memory_address: (*header).p_vaddr as usize,
+            })
+            .collect(),
+        bias: info.dlpi_addr as usize,
+    });
+    0
+}
diff --git a/vendor/backtrace/src/symbolize/gimli/libs_haiku.rs b/vendor/backtrace/src/symbolize/gimli/libs_haiku.rs
new file mode 100644
index 0000000..87e023e
--- /dev/null
+++ b/vendor/backtrace/src/symbolize/gimli/libs_haiku.rs
@@ -0,0 +1,48 @@
+// Haiku implements the image_info struct and the get_next_image_info()
+// functions to iterate through the loaded executable images. The
+// image_info struct contains a pointer to the start of the .text
+// section within the virtual address space, as well as the size of
+// that section. All the read-only segments of the ELF-binary are in
+// that part of the address space.
+
+use super::mystd::borrow::ToOwned;
+use super::mystd::ffi::{CStr, OsStr};
+use super::mystd::mem::MaybeUninit;
+use super::mystd::os::unix::prelude::*;
+use super::{Library, LibrarySegment, Vec};
+
+pub(super) fn native_libraries() -> Vec<Library> {
+    let mut libraries: Vec<Library> = Vec::new();
+
+    unsafe {
+        let mut info = MaybeUninit::<libc::image_info>::zeroed();
+        let mut cookie: i32 = 0;
+        // Load the first image to get a valid info struct
+        let mut status =
+            libc::get_next_image_info(libc::B_CURRENT_TEAM, &mut cookie, info.as_mut_ptr());
+        if status != libc::B_OK {
+            return libraries;
+        }
+        let mut info = info.assume_init();
+
+        while status == libc::B_OK {
+            let mut segments = Vec::new();
+            segments.push(LibrarySegment {
+                stated_virtual_memory_address: 0,
+                len: info.text_size as usize,
+            });
+
+            let bytes = CStr::from_ptr(info.name.as_ptr()).to_bytes();
+            let name = OsStr::from_bytes(bytes).to_owned();
+            libraries.push(Library {
+                name: name,
+                segments: segments,
+                bias: info.text as usize,
+            });
+
+            status = libc::get_next_image_info(libc::B_CURRENT_TEAM, &mut cookie, &mut info);
+        }
+    }
+
+    libraries
+}
diff --git a/vendor/backtrace/src/symbolize/gimli/libs_illumos.rs b/vendor/backtrace/src/symbolize/gimli/libs_illumos.rs
new file mode 100644
index 0000000..e64975e
--- /dev/null
+++ b/vendor/backtrace/src/symbolize/gimli/libs_illumos.rs
@@ -0,0 +1,99 @@
+use super::mystd::borrow::ToOwned;
+use super::mystd::ffi::{CStr, OsStr};
+use super::mystd::os::unix::prelude::*;
+use super::{Library, LibrarySegment, Vec};
+use core::mem;
+use object::NativeEndian;
+
+#[cfg(target_pointer_width = "64")]
+use object::elf::{FileHeader64 as FileHeader, ProgramHeader64 as ProgramHeader};
+
+type EHdr = FileHeader<NativeEndian>;
+type PHdr = ProgramHeader<NativeEndian>;
+
+#[repr(C)]
+struct LinkMap {
+    l_addr: libc::c_ulong,
+    l_name: *const libc::c_char,
+    l_ld: *const libc::c_void,
+    l_next: *const LinkMap,
+    l_prev: *const LinkMap,
+    l_refname: *const libc::c_char,
+}
+
+const RTLD_SELF: *const libc::c_void = -3isize as *const libc::c_void;
+const RTLD_DI_LINKMAP: libc::c_int = 2;
+
+extern "C" {
+    fn dlinfo(
+        handle: *const libc::c_void,
+        request: libc::c_int,
+        p: *mut libc::c_void,
+    ) -> libc::c_int;
+}
+
+pub(super) fn native_libraries() -> Vec<Library> {
+    let mut libs = Vec::new();
+
+    // Request the current link map from the runtime linker:
+    let map = unsafe {
+        let mut map: *const LinkMap = mem::zeroed();
+        if dlinfo(
+            RTLD_SELF,
+            RTLD_DI_LINKMAP,
+            (&mut map) as *mut *const LinkMap as *mut libc::c_void,
+        ) != 0
+        {
+            return libs;
+        }
+        map
+    };
+
+    // Each entry in the link map represents a loaded object:
+    let mut l = map;
+    while !l.is_null() {
+        // Fetch the fully qualified path of the loaded object:
+        let bytes = unsafe { CStr::from_ptr((*l).l_name) }.to_bytes();
+        let name = OsStr::from_bytes(bytes).to_owned();
+
+        // The base address of the object loaded into memory:
+        let addr = unsafe { (*l).l_addr };
+
+        // Use the ELF header for this object to locate the program
+        // header:
+        let e: *const EHdr = unsafe { (*l).l_addr as *const EHdr };
+        let phoff = unsafe { (*e).e_phoff }.get(NativeEndian);
+        let phnum = unsafe { (*e).e_phnum }.get(NativeEndian);
+        let etype = unsafe { (*e).e_type }.get(NativeEndian);
+
+        let phdr: *const PHdr = (addr + phoff) as *const PHdr;
+        let phdr = unsafe { core::slice::from_raw_parts(phdr, phnum as usize) };
+
+        libs.push(Library {
+            name,
+            segments: phdr
+                .iter()
+                .map(|p| {
+                    let memsz = p.p_memsz.get(NativeEndian);
+                    let vaddr = p.p_vaddr.get(NativeEndian);
+                    LibrarySegment {
+                        len: memsz as usize,
+                        stated_virtual_memory_address: vaddr as usize,
+                    }
+                })
+                .collect(),
+            bias: if etype == object::elf::ET_EXEC {
+                // Program header addresses for the base executable are
+                // already absolute.
+                0
+            } else {
+                // Other addresses are relative to the object base.
+                addr as usize
+            },
+        });
+
+        l = unsafe { (*l).l_next };
+    }
+
+    libs
+}
diff --git a/vendor/backtrace/src/symbolize/gimli/libs_libnx.rs b/vendor/backtrace/src/symbolize/gimli/libs_libnx.rs
new file mode 100644
index 0000000..93b5ba1
--- /dev/null
+++ b/vendor/backtrace/src/symbolize/gimli/libs_libnx.rs
@@ -0,0 +1,27 @@
+use super::{Library, LibrarySegment, Vec};
+
+// DevkitA64 doesn't natively support debug info, but the build system will
+// place debug info at the path `romfs:/debug_info.elf`.
+pub(super) fn native_libraries() -> Vec<Library> {
+    extern "C" {
+        static __start__: u8;
+    }
+
+    let bias = unsafe { &__start__ } as *const u8 as usize;
+
+    let mut ret = Vec::new();
+    let mut segments = Vec::new();
+    segments.push(LibrarySegment {
+        stated_virtual_memory_address: 0,
+        len: usize::max_value() - bias,
+    });
+
+    let path = "romfs:/debug_info.elf";
+    ret.push(Library {
+        name: path.into(),
+        segments,
+        bias,
+    });
+
+    ret
+}
diff --git a/vendor/backtrace/src/symbolize/gimli/libs_macos.rs b/vendor/backtrace/src/symbolize/gimli/libs_macos.rs
new file mode 100644
index 0000000..438bbff
--- /dev/null
+++ b/vendor/backtrace/src/symbolize/gimli/libs_macos.rs
@@ -0,0 +1,146 @@
+#![allow(deprecated)]
+
+use super::mystd::ffi::{CStr, OsStr};
+use super::mystd::os::unix::prelude::*;
+use super::mystd::prelude::v1::*;
+use super::{Library, LibrarySegment};
+use core::convert::TryInto;
+use core::mem;
+
+pub(super) fn native_libraries() -> Vec<Library> {
+    let mut ret = Vec::new();
+    let images = unsafe { libc::_dyld_image_count() };
+    for i in 0..images {
+        ret.extend(native_library(i));
+    }
+    return ret;
+}
+
+fn native_library(i: u32) -> Option<Library> {
+    use object::macho;
+    use object::read::macho::{MachHeader, Segment};
+    use object::NativeEndian;
+
+    // Fetch the name of this library which corresponds to the path of
+    // where to load it as well.
+    let name = unsafe {
+        let name = libc::_dyld_get_image_name(i);
+        if name.is_null() {
+            return None;
+        }
+        CStr::from_ptr(name)
+    };
+
+    // Load the image header of this library and delegate to `object` to
+    // parse all the load commands so we can figure out all the segments
+    // involved here.
+    let (mut load_commands, endian) = unsafe {
+        let header = libc::_dyld_get_image_header(i);
+        if header.is_null() {
+            return None;
+        }
+        match (*header).magic {
+            macho::MH_MAGIC => {
+                let endian = NativeEndian;
+                let header = &*(header as *const macho::MachHeader32<NativeEndian>);
+                let data = core::slice::from_raw_parts(
+                    header as *const _ as *const u8,
+                    mem::size_of_val(header) + header.sizeofcmds.get(endian) as usize,
+                );
+                (header.load_commands(endian, data, 0).ok()?, endian)
+            }
+            macho::MH_MAGIC_64 => {
+                let endian = NativeEndian;
+                let header = &*(header as *const macho::MachHeader64<NativeEndian>);
+                let data = core::slice::from_raw_parts(
+                    header as *const _ as *const u8,
+                    mem::size_of_val(header) + header.sizeofcmds.get(endian) as usize,
+                );
+                (header.load_commands(endian, data, 0).ok()?, endian)
+            }
+            _ => return None,
+        }
+    };
+
+    // Iterate over the segments and register known regions for segments
+    // that we find. Additionally record information bout text segments
+    // for processing later, see comments below.
+    let mut segments = Vec::new();
+    let mut first_text = 0;
+    let mut text_fileoff_zero = false;
+    while let Some(cmd) = load_commands.next().ok()? {
+        if let Some((seg, _)) = cmd.segment_32().ok()? {
+            if seg.name() == b"__TEXT" {
+                first_text = segments.len();
+                if seg.fileoff(endian) == 0 && seg.filesize(endian) > 0 {
+                    text_fileoff_zero = true;
+                }
+            }
+            segments.push(LibrarySegment {
+                len: seg.vmsize(endian).try_into().ok()?,
+                stated_virtual_memory_address: seg.vmaddr(endian).try_into().ok()?,
+            });
+        }
+        if let Some((seg, _)) = cmd.segment_64().ok()? {
+            if seg.name() == b"__TEXT" {
+                first_text = segments.len();
+                if seg.fileoff(endian) == 0 && seg.filesize(endian) > 0 {
+                    text_fileoff_zero = true;
+                }
+            }
+            segments.push(LibrarySegment {
+                len: seg.vmsize(endian).try_into().ok()?,
+                stated_virtual_memory_address: seg.vmaddr(endian).try_into().ok()?,
+            });
+        }
+    }
+
+    // Determine the "slide" for this library which ends up being the
+    // bias we use to figure out where in memory objects are loaded.
+    // This is a bit of a weird computation though and is the result of
+    // trying a few things in the wild and seeing what sticks.
+    //
+    // The general idea is that the `bias` plus a segment's
+    // `stated_virtual_memory_address` is going to be where in the
+    // actual address space the segment resides. The other thing we rely
+    // on though is that a real address minus the `bias` is the index to
+    // look up in the symbol table and debuginfo.
+    //
+    // It turns out, though, that for system loaded libraries these
+    // calculations are incorrect. For native executables, however, it
+    // appears correct. Lifting some logic from LLDB's source it has
+    // some special-casing for the first `__TEXT` section loaded from
+    // file offset 0 with a nonzero size. For whatever reason when this
+    // is present it appears to mean that the symbol table is relative
+    // to just the vmaddr slide for the library. If it's *not* present
+    // then the symbol table is relative to the vmaddr slide plus the
+    // segment's stated address.
+    //
+    // To handle this situation if we *don't* find a text section at
+    // file offset zero then we increase the bias by the first text
+    // sections's stated address and decrease all stated addresses by
+    // that amount as well. That way the symbol table is always appears
+    // relative to the library's bias amount. This appears to have the
+    // right results for symbolizing via the symbol table.
+    //
+    // Honestly I'm not entirely sure whether this is right or if
+    // there's something else that should indicate how to do this. For
+    // now though this seems to work well enough (?) and we should
+    // always be able to tweak this over time if necessary.
+    //
+    // For some more information see #318
+    let mut slide = unsafe { libc::_dyld_get_image_vmaddr_slide(i) as usize };
+    if !text_fileoff_zero {
+        let adjust = segments[first_text].stated_virtual_memory_address;
+        for segment in segments.iter_mut() {
+            segment.stated_virtual_memory_address -= adjust;
+        }
+        slide += adjust;
+    }
+
+    Some(Library {
+        name: OsStr::from_bytes(name.to_bytes()).to_owned(),
+        segments,
+        bias: slide,
+    })
+}
diff --git a/vendor/backtrace/src/symbolize/gimli/libs_windows.rs b/vendor/backtrace/src/symbolize/gimli/libs_windows.rs
new file mode 100644
index 0000000..b47ed42
--- /dev/null
+++ b/vendor/backtrace/src/symbolize/gimli/libs_windows.rs
@@ -0,0 +1,89 @@
+use super::super::super::windows::*;
+use super::mystd::os::windows::prelude::*;
+use super::{coff, mmap, Library, LibrarySegment, OsString};
+use alloc::vec;
+use alloc::vec::Vec;
+use core::mem;
+use core::mem::MaybeUninit;
+
+// For loading native libraries on Windows, see some discussion on
+// rust-lang/rust#71060 for the various strategies here.
+pub(super) fn native_libraries() -> Vec<Library> {
+    let mut ret = Vec::new();
+    unsafe {
+        add_loaded_images(&mut ret);
+    }
+    return ret;
+}
+
+unsafe fn add_loaded_images(ret: &mut Vec<Library>) {
+    let snap = CreateToolhelp32Snapshot(TH32CS_SNAPMODULE, 0);
+    if snap == INVALID_HANDLE_VALUE {
+        return;
+    }
+
+    let mut me = MaybeUninit::<MODULEENTRY32W>::zeroed().assume_init();
+    me.dwSize = mem::size_of_val(&me) as DWORD;
+    if Module32FirstW(snap, &mut me) == TRUE {
+        loop {
+            if let Some(lib) = load_library(&me) {
+                ret.push(lib);
+            }
+
+            if Module32NextW(snap, &mut me) != TRUE {
+                break;
+            }
+        }
+    }
+
+    CloseHandle(snap);
+}
+
+unsafe fn load_library(me: &MODULEENTRY32W) -> Option<Library> {
+    let pos = me
+        .szExePath
+        .iter()
+        .position(|i| *i == 0)
+        .unwrap_or(me.szExePath.len());
+    let name = OsString::from_wide(&me.szExePath[..pos]);
+
+    // MinGW libraries currently don't support ASLR
+    // (rust-lang/rust#16514), but DLLs can still be relocated around in
+    // the address space. It appears that addresses in debug info are
+    // all as-if this library was loaded at its "image base", which is a
+    // field in its COFF file headers. Since this is what debuginfo
+    // seems to list we parse the symbol table and store addresses as if
+    // the library was loaded at "image base" as well.
+    //
+    // The library may not be loaded at "image base", however.
+    // (presumably something else may be loaded there?) This is where
+    // the `bias` field comes into play, and we need to figure out the
+    // value of `bias` here. Unfortunately though it's not clear how to
+    // acquire this from a loaded module. What we do have, however, is
+    // the actual load address (`modBaseAddr`).
+    //
+    // As a bit of a cop-out for now we mmap the file, read the file
+    // header information, then drop the mmap. This is wasteful because
+    // we'll probably reopen the mmap later, but this should work well
+    // enough for now.
+    //
+    // Once we have the `image_base` (desired load location) and the
+    // `base_addr` (actual load location) we can fill in the `bias`
+    // (difference between the actual and desired) and then the stated
+    // address of each segment is the `image_base` since that's what the
+    // file says.
+    //
+    // For now it appears that unlike ELF/MachO we can make do with one
+    // segment per library, using `modBaseSize` as the whole size.
+    let mmap = mmap(name.as_ref())?;
+    let image_base = coff::get_image_base(&mmap)?;
+    let base_addr = me.modBaseAddr as usize;
+    Some(Library {
+        name,
+        bias: base_addr.wrapping_sub(image_base),
+        segments: vec![LibrarySegment {
+            stated_virtual_memory_address: image_base,
+            len: me.modBaseSize as usize,
+        }],
+    })
+}
diff --git a/vendor/backtrace/src/symbolize/gimli/macho.rs b/vendor/backtrace/src/symbolize/gimli/macho.rs
new file mode 100644
index 0000000..74ed809
--- /dev/null
+++ b/vendor/backtrace/src/symbolize/gimli/macho.rs
@@ -0,0 +1,333 @@
+use super::{gimli, Box, Context, Endian, EndianSlice, Mapping, Path, Stash, Vec};
+use alloc::sync::Arc;
+use core::convert::TryInto;
+use object::macho;
+use object::read::macho::{MachHeader, Nlist, Section, Segment as _};
+use object::{Bytes, NativeEndian};
+
+#[cfg(target_pointer_width = "32")]
+type Mach = object::macho::MachHeader32<NativeEndian>;
+#[cfg(target_pointer_width = "64")]
+type Mach = object::macho::MachHeader64<NativeEndian>;
+type MachSegment = <Mach as MachHeader>::Segment;
+type MachSection = <Mach as MachHeader>::Section;
+type MachNlist = <Mach as MachHeader>::Nlist;
+
+impl Mapping {
+    // The loading path for macOS is so different we just have a completely
+    // different implementation of the function here. On macOS we need to go
+    // probing the filesystem for a bunch of files.
+    pub fn new(path: &Path) -> Option<Mapping> {
+        // First up we need to load the unique UUID which is stored in the macho
+        // header of the file we're reading, specified at `path`.
+        let map = super::mmap(path)?;
+        let (macho, data) = find_header(&map)?;
+        let endian = macho.endian().ok()?;
+        let uuid = macho.uuid(endian, data, 0).ok()?;
+
+        // Next we need to look for a `*.dSYM` file. For now we just probe the
+        // containing directory and look around for something that matches
+        // `*.dSYM`. Once it's found we root through the dwarf resources that it
+        // contains and try to find a macho file which has a matching UUID as
+        // the one of our own file. If we find a match that's the dwarf file we
+        // want to return.
+        if let Some(uuid) = uuid {
+            if let Some(parent) = path.parent() {
+                if let Some(mapping) = Mapping::load_dsym(parent, uuid) {
+                    return Some(mapping);
+                }
+            }
+        }
+
+        // Looks like nothing matched our UUID, so let's at least return our own
+        // file. This should have the symbol table for at least some
+        // symbolication purposes.
+        Mapping::mk(map, |data, stash| {
+            let (macho, data) = find_header(data)?;
+            let endian = macho.endian().ok()?;
+            let obj = Object::parse(macho, endian, data)?;
+            Context::new(stash, obj, None, None)
+        })
+    }
+
+    fn load_dsym(dir: &Path, uuid: [u8; 16]) -> Option<Mapping> {
+        for entry in dir.read_dir().ok()? {
+            let entry = entry.ok()?;
+            let filename = match entry.file_name().into_string() {
+                Ok(name) => name,
+                Err(_) => continue,
+            };
+            if !filename.ends_with(".dSYM") {
+                continue;
+            }
+            let candidates = entry.path().join("Contents/Resources/DWARF");
+            if let Some(mapping) = Mapping::try_dsym_candidate(&candidates, uuid) {
+                return Some(mapping);
+            }
+        }
+        None
+    }
+
+    fn try_dsym_candidate(dir: &Path, uuid: [u8; 16]) -> Option<Mapping> {
+        // Look for files in the `DWARF` directory which have a matching uuid to
+        // the original object file. If we find one then we found the debug
+        // information.
+        for entry in dir.read_dir().ok()? {
+            let entry = entry.ok()?;
+            let map = super::mmap(&entry.path())?;
+            let candidate = Mapping::mk(map, |data, stash| {
+                let (macho, data) = find_header(data)?;
+                let endian = macho.endian().ok()?;
+                let entry_uuid = macho.uuid(endian, data, 0).ok()??;
+                if entry_uuid != uuid {
+                    return None;
+                }
+                let obj = Object::parse(macho, endian, data)?;
+                Context::new(stash, obj, None, None)
+            });
+            if let Some(candidate) = candidate {
+                return Some(candidate);
+            }
+        }
+
+        None
+    }
+}
+
+fn find_header(data: &'_ [u8]) -> Option<(&'_ Mach, &'_ [u8])> {
+    use object::endian::BigEndian;
+
+    let desired_cpu = || {
+        if cfg!(target_arch = "x86") {
+            Some(macho::CPU_TYPE_X86)
+        } else if cfg!(target_arch = "x86_64") {
+            Some(macho::CPU_TYPE_X86_64)
+        } else if cfg!(target_arch = "arm") {
+            Some(macho::CPU_TYPE_ARM)
+        } else if cfg!(target_arch = "aarch64") {
+            Some(macho::CPU_TYPE_ARM64)
+        } else {
+            None
+        }
+    };
+
+    let mut data = Bytes(data);
+    match data
+        .clone()
+        .read::<object::endian::U32<NativeEndian>>()
+        .ok()?
+        .get(NativeEndian)
+    {
+        macho::MH_MAGIC_64 | macho::MH_CIGAM_64 | macho::MH_MAGIC | macho::MH_CIGAM => {}
+
+        macho::FAT_MAGIC | macho::FAT_CIGAM => {
+            let mut header_data = data;
+            let endian = BigEndian;
+            let header = header_data.read::<macho::FatHeader>().ok()?;
+            let nfat = header.nfat_arch.get(endian);
+            let arch = (0..nfat)
+                .filter_map(|_| header_data.read::<macho::FatArch32>().ok())
+                .find(|arch| desired_cpu() == Some(arch.cputype.get(endian)))?;
+            let offset = arch.offset.get(endian);
+            let size = arch.size.get(endian);
+            data = data
+                .read_bytes_at(offset.try_into().ok()?, size.try_into().ok()?)
+                .ok()?;
+        }
+
+        macho::FAT_MAGIC_64 | macho::FAT_CIGAM_64 => {
+            let mut header_data = data;
+            let endian = BigEndian;
+            let header = header_data.read::<macho::FatHeader>().ok()?;
+            let nfat = header.nfat_arch.get(endian);
+            let arch = (0..nfat)
+                .filter_map(|_| header_data.read::<macho::FatArch64>().ok())
+                .find(|arch| desired_cpu() == Some(arch.cputype.get(endian)))?;
+            let offset = arch.offset.get(endian);
+            let size = arch.size.get(endian);
+            data = data
+                .read_bytes_at(offset.try_into().ok()?, size.try_into().ok()?)
+                .ok()?;
+        }
+
+        _ => return None,
+    }
+
+    Mach::parse(data.0, 0).ok().map(|h| (h, data.0))
+}
+
+// This is used both for executables/libraries and source object files.
+pub struct Object<'a> {
+    endian: NativeEndian,
+    data: &'a [u8],
+    dwarf: Option<&'a [MachSection]>,
+    syms: Vec<(&'a [u8], u64)>,
+    syms_sort_by_name: bool,
+    // Only set for executables/libraries, and not the source object files.
+    object_map: Option<object::ObjectMap<'a>>,
+    // The outer Option is for lazy loading, and the inner Option allows load errors to be cached.
+    object_mappings: Box<[Option<Option<Mapping>>]>,
+}
+
+impl<'a> Object<'a> {
+    fn parse(mach: &'a Mach, endian: NativeEndian, data: &'a [u8]) -> Option<Object<'a>> {
+        let is_object = mach.filetype(endian) == object::macho::MH_OBJECT;
+        let mut dwarf = None;
+        let mut syms = Vec::new();
+        let mut syms_sort_by_name = false;
+        let mut commands = mach.load_commands(endian, data, 0).ok()?;
+        let mut object_map = None;
+        let mut object_mappings = Vec::new();
+        while let Ok(Some(command)) = commands.next() {
+            if let Some((segment, section_data)) = MachSegment::from_command(command).ok()? {
+                // Object files should have all sections in a single unnamed segment load command.
+                if segment.name() == b"__DWARF" || (is_object && segment.name() == b"") {
+                    dwarf = segment.sections(endian, section_data).ok();
+                }
+            } else if let Some(symtab) = command.symtab().ok()? {
+                let symbols = symtab.symbols::<Mach, _>(endian, data).ok()?;
+                syms = symbols
+                    .iter()
+                    .filter_map(|nlist: &MachNlist| {
+                        let name = nlist.name(endian, symbols.strings()).ok()?;
+                        if name.len() > 0 && nlist.is_definition() {
+                            Some((name, u64::from(nlist.n_value(endian))))
+                        } else {
+                            None
+                        }
+                    })
+                    .collect();
+                if is_object {
+                    // We never search object file symbols by address.
+                    // Instead, we already know the symbol name from the executable, and we
+                    // need to search by name to find the matching symbol in the object file.
+                    syms.sort_unstable_by_key(|(name, _)| *name);
+                    syms_sort_by_name = true;
+                } else {
+                    syms.sort_unstable_by_key(|(_, addr)| *addr);
+                    let map = symbols.object_map(endian);
+                    object_mappings.resize_with(map.objects().len(), || None);
+                    object_map = Some(map);
+                }
+            }
+        }
+
+        Some(Object {
+            endian,
+            data,
+            dwarf,
+            syms,
+            syms_sort_by_name,
+            object_map,
+            object_mappings: object_mappings.into_boxed_slice(),
+        })
+    }
+
+    pub fn section(&self, _: &Stash, name: &str) -> Option<&'a [u8]> {
+        let name = name.as_bytes();
+        let dwarf = self.dwarf?;
+        let section = dwarf.into_iter().find(|section| {
+            let section_name = section.name();
+            section_name == name || {
+                section_name.starts_with(b"__")
+                    && name.starts_with(b".")
+                    && &section_name[2..] == &name[1..]
+            }
+        })?;
+        Some(section.data(self.endian, self.data).ok()?)
+    }
+
+    pub fn search_symtab<'b>(&'b self, addr: u64) -> Option<&'b [u8]> {
+        debug_assert!(!self.syms_sort_by_name);
+        let i = match self.syms.binary_search_by_key(&addr, |(_, addr)| *addr) {
+            Ok(i) => i,
+            Err(i) => i.checked_sub(1)?,
+        };
+        let (sym, _addr) = self.syms.get(i)?;
+        Some(sym)
+    }
+
+    /// Try to load a context for an object file.
+    ///
+    /// If dsymutil was not run, then the DWARF may be found in the source object files.
+    pub(super) fn search_object_map<'b>(&'b mut self, addr: u64) -> Option<(&Context<'b>, u64)> {
+        // `object_map` contains a map from addresses to symbols and object paths.
+        // Look up the address and get a mapping for the object.
+        let object_map = self.object_map.as_ref()?;
+        let symbol = object_map.get(addr)?;
+        let object_index = symbol.object_index();
+        let mapping = self.object_mappings.get_mut(object_index)?;
+        if mapping.is_none() {
+            // No cached mapping, so create it.
+            *mapping = Some(object_mapping(object_map.objects().get(object_index)?));
+        }
+        let cx: &'b Context<'static> = &mapping.as_ref()?.as_ref()?.cx;
+        // Don't leak the `'static` lifetime, make sure it's scoped to just ourselves.
+        let cx = unsafe { core::mem::transmute::<&'b Context<'static>, &'b Context<'b>>(cx) };
+
+        // We must translate the address in order to be able to look it up
+        // in the DWARF in the object file.
+        debug_assert!(cx.object.syms.is_empty() || cx.object.syms_sort_by_name);
+        let i = cx
+            .object
+            .syms
+            .binary_search_by_key(&symbol.name(), |(name, _)| *name)
+            .ok()?;
+        let object_symbol = cx.object.syms.get(i)?;
+        let object_addr = addr
+            .wrapping_sub(symbol.address())
+            .wrapping_add(object_symbol.1);
+        Some((cx, object_addr))
+    }
+}
+
+fn object_mapping(path: &[u8]) -> Option<Mapping> {
+    use super::mystd::ffi::OsStr;
+    use super::mystd::os::unix::prelude::*;
+
+    let map;
+
+    // `N_OSO` symbol names can be either `/path/to/object.o` or `/path/to/archive.a(object.o)`.
+    let member_name = if let Some((archive_path, member_name)) = split_archive_path(path) {
+        map = super::mmap(Path::new(OsStr::from_bytes(archive_path)))?;
+        Some(member_name)
+    } else {
+        map = super::mmap(Path::new(OsStr::from_bytes(path)))?;
+        None
+    };
+    Mapping::mk(map, |data, stash| {
+        let data = match member_name {
+            Some(member_name) => {
+                let archive = object::read::archive::ArchiveFile::parse(data).ok()?;
+                let member = archive
+                    .members()
+                    .filter_map(Result::ok)
+                    .find(|m| m.name() == member_name)?;
+                member.data(data).ok()?
+            }
+            None => data,
+        };
+        let (macho, data) = find_header(data)?;
+        let endian = macho.endian().ok()?;
+        let obj = Object::parse(macho, endian, data)?;
+        Context::new(stash, obj, None, None)
+    })
+}
+
+fn split_archive_path(path: &[u8]) -> Option<(&[u8], &[u8])> {
+    let (last, path) = path.split_last()?;
+    if *last != b')' {
+        return None;
+    }
+    let index = path.iter().position(|&x| x == b'(')?;
+    let (archive, rest) = path.split_at(index);
+    Some((archive, &rest[1..]))
+}
+
+pub(super) fn handle_split_dwarf<'data>(
+    _package: Option<&gimli::DwarfPackage<EndianSlice<'data, Endian>>>,
+    _stash: &'data Stash,
+    _load: addr2line::SplitDwarfLoad<EndianSlice<'data, Endian>>,
+) -> Option<Arc<gimli::Dwarf<EndianSlice<'data, Endian>>>> {
+    None
+}
diff --git a/vendor/backtrace/src/symbolize/gimli/mmap_fake.rs b/vendor/backtrace/src/symbolize/gimli/mmap_fake.rs
new file mode 100644
index 0000000..ce50964
--- /dev/null
+++ b/vendor/backtrace/src/symbolize/gimli/mmap_fake.rs
@@ -0,0 +1,25 @@
+use super::{mystd::io::Read, File};
+use alloc::vec::Vec;
+use core::ops::Deref;
+
+pub struct Mmap {
+    vec: Vec<u8>,
+}
+
+impl Mmap {
+    pub unsafe fn map(mut file: &File, len: usize) -> Option<Mmap> {
+        let mut mmap = Mmap {
+            vec: Vec::with_capacity(len),
+        };
+        file.read_to_end(&mut mmap.vec).ok()?;
+        Some(mmap)
+    }
+}
+
+impl Deref for Mmap {
+    type Target = [u8];
+
+    fn deref(&self) -> &[u8] {
+        &self.vec[..]
+    }
+}
diff --git a/vendor/backtrace/src/symbolize/gimli/mmap_unix.rs b/vendor/backtrace/src/symbolize/gimli/mmap_unix.rs
new file mode 100644
index 0000000..261ffc1
--- /dev/null
+++ b/vendor/backtrace/src/symbolize/gimli/mmap_unix.rs
@@ -0,0 +1,49 @@
+use super::mystd::fs::File;
+use super::mystd::os::unix::prelude::*;
+use core::ops::Deref;
+use core::ptr;
+use core::slice;
+
+#[cfg(not(all(target_os = "linux", target_env = "gnu")))]
+use libc::mmap as mmap64;
+#[cfg(all(target_os = "linux", target_env = "gnu"))]
+use libc::mmap64;
+
+pub struct Mmap {
+    ptr: *mut libc::c_void,
+    len: usize,
+}
+
+impl Mmap {
+    pub unsafe fn map(file: &File, len: usize) -> Option<Mmap> {
+        let ptr = mmap64(
+            ptr::null_mut(),
+            len,
+            libc::PROT_READ,
+            libc::MAP_PRIVATE,
+            file.as_raw_fd(),
+            0,
+        );
+        if ptr == libc::MAP_FAILED {
+            return None;
+        }
+        Some(Mmap { ptr, len })
+    }
+}
+
+impl Deref for Mmap {
+    type Target = [u8];
+
+    fn deref(&self) -> &[u8] {
+        unsafe { slice::from_raw_parts(self.ptr as *const u8, self.len) }
+    }
+}
+
+impl Drop for Mmap {
+    fn drop(&mut self) {
+        unsafe {
+            let r = libc::munmap(self.ptr, self.len);
+            debug_assert_eq!(r, 0);
+        }
+    }
+}
diff --git a/vendor/backtrace/src/symbolize/gimli/mmap_windows.rs b/vendor/backtrace/src/symbolize/gimli/mmap_windows.rs
new file mode 100644
index 0000000..b39509d
--- /dev/null
+++ b/vendor/backtrace/src/symbolize/gimli/mmap_windows.rs
@@ -0,0 +1,57 @@
+use super::super::super::windows::*;
+use super::mystd::fs::File;
+use super::mystd::os::windows::prelude::*;
+use core::ops::Deref;
+use core::ptr;
+use core::slice;
+
+pub struct Mmap {
+    // keep the file alive to prevent it from being deleted which would cause
+    // us to read bad data.
+    _file: File,
+    ptr: *mut c_void,
+    len: usize,
+}
+
+impl Mmap {
+    pub unsafe fn map(file: &File, len: usize) -> Option<Mmap> {
+        let file = file.try_clone().ok()?;
+        let mapping = CreateFileMappingA(
+            file.as_raw_handle() as *mut _,
+            ptr::null_mut(),
+            PAGE_READONLY,
+            0,
+            0,
+            ptr::null(),
+        );
+        if mapping.is_null() {
+            return None;
+        }
+        let ptr = MapViewOfFile(mapping, FILE_MAP_READ, 0, 0, len);
+        CloseHandle(mapping);
+        if ptr.is_null() {
+            return None;
+        }
+        Some(Mmap {
+            _file: file,
+            ptr,
+            len,
+        })
+    }
+}
+impl Deref for Mmap {
+    type Target = [u8];
+
+    fn deref(&self) -> &[u8] {
+        unsafe { slice::from_raw_parts(self.ptr as *const u8, self.len) }
+    }
+}
+
+impl Drop for Mmap {
+    fn drop(&mut self) {
+        unsafe {
+            let r = UnmapViewOfFile(self.ptr);
+            debug_assert!(r != 0);
+        }
+    }
+}
diff --git a/vendor/backtrace/src/symbolize/gimli/parse_running_mmaps_unix.rs b/vendor/backtrace/src/symbolize/gimli/parse_running_mmaps_unix.rs
new file mode 100644
index 0000000..5d4b346
--- /dev/null
+++ b/vendor/backtrace/src/symbolize/gimli/parse_running_mmaps_unix.rs
@@ -0,0 +1,295 @@
+// Note: This file is only currently used on targets that call out to the code
+// in `mod libs_dl_iterate_phdr` (e.g. linux, freebsd, ...); it may be more
+// general purpose, but it hasn't been tested elsewhere.
+
+use super::mystd::fs::File;
+use super::mystd::io::Read;
+use super::mystd::str::FromStr;
+use super::{OsString, String, Vec};
+
+#[derive(PartialEq, Eq, Debug)]
+pub(super) struct MapsEntry {
+    /// start (inclusive) and limit (exclusive) of address range.
+    address: (usize, usize),
+    /// The perms field are the permissions for the entry
+    ///
+    /// r = read
+    /// w = write
+    /// x = execute
+    /// s = shared
+    /// p = private (copy on write)
+    perms: [char; 4],
+    /// Offset into the file (or "whatever").
+    offset: usize,
+    /// device (major, minor)
+    dev: (usize, usize),
+    /// inode on the device. 0 indicates that no inode is associated with the memory region (e.g. uninitalized data aka BSS).
+    inode: usize,
+    /// Usually the file backing the mapping.
+    ///
+    /// Note: The man page for proc includes a note about "coordination" by
+    /// using readelf to see the Offset field in ELF program headers. pnkfelix
+    /// is not yet sure if that is intended to be a comment on pathname, or what
+    /// form/purpose such coordination is meant to have.
+    ///
+    /// There are also some pseudo-paths:
+    /// "[stack]": The initial process's (aka main thread's) stack.
+    /// "[stack:<tid>]": a specific thread's stack. (This was only present for a limited range of Linux verisons; it was determined to be too expensive to provide.)
+    /// "[vdso]": Virtual dynamically linked shared object
+    /// "[heap]": The process's heap
+    ///
+    /// The pathname can be blank, which means it is an anonymous mapping
+    /// obtained via mmap.
+    ///
+    /// Newlines in pathname are replaced with an octal escape sequence.
+    ///
+    /// The pathname may have "(deleted)" appended onto it if the file-backed
+    /// path has been deleted.
+    ///
+    /// Note that modifications like the latter two indicated above imply that
+    /// in general the pathname may be ambiguous. (I.e. you cannot tell if the
+    /// denoted filename actually ended with the text "(deleted)", or if that
+    /// was added by the maps rendering.
+    pathname: OsString,
+}
+
+pub(super) fn parse_maps() -> Result<Vec<MapsEntry>, &'static str> {
+    let mut v = Vec::new();
+    let mut proc_self_maps =
+        File::open("/proc/self/maps").map_err(|_| "Couldn't open /proc/self/maps")?;
+    let mut buf = String::new();
+    let _bytes_read = proc_self_maps
+        .read_to_string(&mut buf)
+        .map_err(|_| "Couldn't read /proc/self/maps")?;
+    for line in buf.lines() {
+        v.push(line.parse()?);
+    }
+
+    Ok(v)
+}
+
+impl MapsEntry {
+    pub(super) fn pathname(&self) -> &OsString {
+        &self.pathname
+    }
+
+    pub(super) fn ip_matches(&self, ip: usize) -> bool {
+        self.address.0 <= ip && ip < self.address.1
+    }
+}
+
+impl FromStr for MapsEntry {
+    type Err = &'static str;
+
+    // Format: address perms offset dev inode pathname
+    // e.g.: "ffffffffff600000-ffffffffff601000 --xp 00000000 00:00 0                  [vsyscall]"
+    // e.g.: "7f5985f46000-7f5985f48000 rw-p 00039000 103:06 76021795                  /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2"
+    // e.g.: "35b1a21000-35b1a22000 rw-p 00000000 00:00 0"
+    //
+    // Note that paths may contain spaces, so we can't use `str::split` for parsing (until
+    // Split::remainder is stabilized #77998).
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let (range_str, s) = s.trim_start().split_once(' ').unwrap_or((s, ""));
+        if range_str.is_empty() {
+            return Err("Couldn't find address");
+        }
+
+        let (perms_str, s) = s.trim_start().split_once(' ').unwrap_or((s, ""));
+        if perms_str.is_empty() {
+            return Err("Couldn't find permissions");
+        }
+
+        let (offset_str, s) = s.trim_start().split_once(' ').unwrap_or((s, ""));
+        if offset_str.is_empty() {
+            return Err("Couldn't find offset");
+        }
+
+        let (dev_str, s) = s.trim_start().split_once(' ').unwrap_or((s, ""));
+        if dev_str.is_empty() {
+            return Err("Couldn't find dev");
+        }
+
+        let (inode_str, s) = s.trim_start().split_once(' ').unwrap_or((s, ""));
+        if inode_str.is_empty() {
+            return Err("Couldn't find inode");
+        }
+
+        // Pathname may be omitted in which case it will be empty
+        let pathname_str = s.trim_start();
+
+        let hex = |s| usize::from_str_radix(s, 16).map_err(|_| "Couldn't parse hex number");
+        let address = if let Some((start, limit)) = range_str.split_once('-') {
+            (hex(start)?, hex(limit)?)
+        } else {
+            return Err("Couldn't parse address range");
+        };
+        let perms: [char; 4] = {
+            let mut chars = perms_str.chars();
+            let mut c = || chars.next().ok_or("insufficient perms");
+            let perms = [c()?, c()?, c()?, c()?];
+            if chars.next().is_some() {
+                return Err("too many perms");
+            }
+            perms
+        };
+        let offset = hex(offset_str)?;
+        let dev = if let Some((major, minor)) = dev_str.split_once(':') {
+            (hex(major)?, hex(minor)?)
+        } else {
+            return Err("Couldn't parse dev");
+        };
+        let inode = hex(inode_str)?;
+        let pathname = pathname_str.into();
+
+        Ok(MapsEntry {
+            address,
+            perms,
+            offset,
+            dev,
+            inode,
+            pathname,
+        })
+    }
+}
+
+// Make sure we can parse 64-bit sample output if we're on a 64-bit target.
+#[cfg(target_pointer_width = "64")]
+#[test]
+fn check_maps_entry_parsing_64bit() {
+    assert_eq!(
+        "ffffffffff600000-ffffffffff601000 --xp 00000000 00:00 0                  \
+                [vsyscall]"
+            .parse::<MapsEntry>()
+            .unwrap(),
+        MapsEntry {
+            address: (0xffffffffff600000, 0xffffffffff601000),
+            perms: ['-', '-', 'x', 'p'],
+            offset: 0x00000000,
+            dev: (0x00, 0x00),
+            inode: 0x0,
+            pathname: "[vsyscall]".into(),
+        }
+    );
+
+    assert_eq!(
+        "7f5985f46000-7f5985f48000 rw-p 00039000 103:06 76021795                  \
+                /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2"
+            .parse::<MapsEntry>()
+            .unwrap(),
+        MapsEntry {
+            address: (0x7f5985f46000, 0x7f5985f48000),
+            perms: ['r', 'w', '-', 'p'],
+            offset: 0x00039000,
+            dev: (0x103, 0x06),
+            inode: 0x76021795,
+            pathname: "/usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2".into(),
+        }
+    );
+    assert_eq!(
+        "35b1a21000-35b1a22000 rw-p 00000000 00:00 0"
+            .parse::<MapsEntry>()
+            .unwrap(),
+        MapsEntry {
+            address: (0x35b1a21000, 0x35b1a22000),
+            perms: ['r', 'w', '-', 'p'],
+            offset: 0x00000000,
+            dev: (0x00, 0x00),
+            inode: 0x0,
+            pathname: Default::default(),
+        }
+    );
+}
+
+// (This output was taken from a 32-bit machine, but will work on any target)
+#[test]
+fn check_maps_entry_parsing_32bit() {
+    /* Example snippet of output:
+    08056000-08077000 rw-p 00000000 00:00 0          [heap]
+    b7c79000-b7e02000 r--p 00000000 08:01 60662705   /usr/lib/locale/locale-archive
+    b7e02000-b7e03000 rw-p 00000000 00:00 0
+        */
+    assert_eq!(
+        "08056000-08077000 rw-p 00000000 00:00 0          \
+                [heap]"
+            .parse::<MapsEntry>()
+            .unwrap(),
+        MapsEntry {
+            address: (0x08056000, 0x08077000),
+            perms: ['r', 'w', '-', 'p'],
+            offset: 0x00000000,
+            dev: (0x00, 0x00),
+            inode: 0x0,
+            pathname: "[heap]".into(),
+        }
+    );
+
+    assert_eq!(
+        "b7c79000-b7e02000 r--p 00000000 08:01 60662705   \
+                /usr/lib/locale/locale-archive"
+            .parse::<MapsEntry>()
+            .unwrap(),
+        MapsEntry {
+            address: (0xb7c79000, 0xb7e02000),
+            perms: ['r', '-', '-', 'p'],
+            offset: 0x00000000,
+            dev: (0x08, 0x01),
+            inode: 0x60662705,
+            pathname: "/usr/lib/locale/locale-archive".into(),
+        }
+    );
+    assert_eq!(
+        "b7e02000-b7e03000 rw-p 00000000 00:00 0"
+            .parse::<MapsEntry>()
+            .unwrap(),
+        MapsEntry {
+            address: (0xb7e02000, 0xb7e03000),
+            perms: ['r', 'w', '-', 'p'],
+            offset: 0x00000000,
+            dev: (0x00, 0x00),
+            inode: 0x0,
+            pathname: Default::default(),
+        }
+    );
+    assert_eq!(
+        "b7c79000-b7e02000 r--p 00000000 08:01 60662705   \
+                /executable/path/with some spaces"
+            .parse::<MapsEntry>()
+            .unwrap(),
+        MapsEntry {
+            address: (0xb7c79000, 0xb7e02000),
+            perms: ['r', '-', '-', 'p'],
+            offset: 0x00000000,
+            dev: (0x08, 0x01),
+            inode: 0x60662705,
+            pathname: "/executable/path/with some spaces".into(),
+        }
+    );
+    assert_eq!(
+        "b7c79000-b7e02000 r--p 00000000 08:01 60662705   \
+                /executable/path/with  multiple-continuous    spaces  "
+            .parse::<MapsEntry>()
+            .unwrap(),
+        MapsEntry {
+            address: (0xb7c79000, 0xb7e02000),
+            perms: ['r', '-', '-', 'p'],
+            offset: 0x00000000,
+            dev: (0x08, 0x01),
+            inode: 0x60662705,
+            pathname: "/executable/path/with  multiple-continuous    spaces  ".into(),
+        }
+    );
+    assert_eq!(
+        "  b7c79000-b7e02000  r--p  00000000  08:01  60662705   \
+                /executable/path/starts-with-spaces"
+            .parse::<MapsEntry>()
+            .unwrap(),
+        MapsEntry {
+            address: (0xb7c79000, 0xb7e02000),
+            perms: ['r', '-', '-', 'p'],
+            offset: 0x00000000,
+            dev: (0x08, 0x01),
+            inode: 0x60662705,
+            pathname: "/executable/path/starts-with-spaces".into(),
+        }
+    );
+}
diff --git a/vendor/backtrace/src/symbolize/gimli/stash.rs b/vendor/backtrace/src/symbolize/gimli/stash.rs
new file mode 100644
index 0000000..792f9a6
--- /dev/null
+++ b/vendor/backtrace/src/symbolize/gimli/stash.rs
@@ -0,0 +1,50 @@
+// only used on Linux right now, so allow dead code elsewhere
+#![cfg_attr(not(target_os = "linux"), allow(dead_code))]
+
+use super::Mmap;
+use alloc::vec;
+use alloc::vec::Vec;
+use core::cell::UnsafeCell;
+
+/// A simple arena allocator for byte buffers.
+pub struct Stash {
+    buffers: UnsafeCell<Vec<Vec<u8>>>,
+    mmaps: UnsafeCell<Vec<Mmap>>,
+}
+
+impl Stash {
+    pub fn new() -> Stash {
+        Stash {
+            buffers: UnsafeCell::new(Vec::new()),
+            mmaps: UnsafeCell::new(Vec::new()),
+        }
+    }
+
+    /// Allocates a buffer of the specified size and returns a mutable reference
+    /// to it.
+    pub fn allocate(&self, size: usize) -> &mut [u8] {
+        // SAFETY: this is the only function that ever constructs a mutable
+        // reference to `self.buffers`.
+        let buffers = unsafe { &mut *self.buffers.get() };
+        let i = buffers.len();
+        buffers.push(vec![0; size]);
+        // SAFETY: we never remove elements from `self.buffers`, so a reference
+        // to the data inside any buffer will live as long as `self` does.
+        &mut buffers[i]
+    }
+
+    /// Stores a `Mmap` for the lifetime of this `Stash`, returning a pointer
+    /// which is scoped to just this lifetime.
+    pub fn cache_mmap(&self, map: Mmap) -> &[u8] {
+        // SAFETY: this is the only location for a mutable pointer to
+        // `mmaps`, and this structure isn't threadsafe to shared across
+        // threads either. We also never remove elements from `self.mmaps`,
+        // so a reference to the data inside the map will live as long as
+        // `self` does.
+        unsafe {
+            let mmaps = &mut *self.mmaps.get();
+            mmaps.push(map);
+            mmaps.last().unwrap()
+        }
+    }
+}